An investigation on the impacts of the skew angle on two bridge piers with respect to the flow direction on the equilibrium scour depth at the piers front

Document Type : Research Article

Authors

1 Shahid Bahonar university of Kerman

2 Shahid Bahonar university of Kerman, Kerman, Iran

3 null

4 Ferdowsi University of Mashhad

5 Ecole polytechnique fédérale de Lausanne (EPFL), switzerland.

Abstract

In this study, the impacts of skew angle of two bridge piers with respect to the flow direction on the equilibrium scour depth in front of the piers under clear water condition is investigated. For this purpose, the piers are aligned with four different skew angles with respect to the flow direction. Additionally, to obtain the equilibrium scour depth in front of the piers, the experiments are performed until reaching the equilibrium time. The results show that increasing the skew-angle increases the equilibrium scour depth and time. The minimum and maximum equilibrium scour depths at both piers occur at the skew-angles of 0 and 60 degree, respectively. Regarding the analysis of the results, the maximum equilibrium scour depths in front of the piers, for the skew angles less than 28 degree occur at the upstream pier while for the skew angles greater than 28 degree is shifted to the downstream pier. In the following, formula are provided to estimate the scour depths in front of the piers, utilizing the Semi-logarithmic linear regression method and observed data.

Keywords


رسول‌زاده، س. و بزرگ حداد، ا. (1387). "مقایسه شبکه عصبی مصنوعی و رگرسیون خطی چند متغیره در پیشبینی میزان آبدهی مخزن سد کرج". سومین کنفرانس مدیریت منابع آب ایران، دانشگاه تبریز، تبریز.
Arneson, P.F.,  Zevenbergen, L.A., and  Lagasse, L. W. (2012). "Evaluating Scour at Bridges". Hydraulic Engineering Circular No. 18 (HEC-18). Rep. No. FHWA NHI 01-001. Federal Highway Administration. Washington. DC.
Ataie-Ashtiani, B. and Beheshti, A.A. (2006). "Experimental investigation of clear-water local scour at pile groups". J. Hydraulic Eng.132(10), pp. 1100–1104.
Cardoso, A.H. and Bettess, R. (1999). "Effects of time and channel geometry on scour at bridge abutments". J. Hydraulic Eng. 125(4), pp. 388-399.
Dey, S., Bose, S.K. and Sastry, G.L.N. (1995). "Clear Water Scour at Circular Piers: a model". J. Hydraulic Eng. 121(12), pp. 869–876.
Dey. S. (2014).  Fluvial Hydrodynamics: Hydrodynamic and Sediment Transport Phenomena, Springer, Berlin.
Ettema, R. (1980). "Scour at bridge piers". Rep. No. 216, University of Auckland, Auckland, New Zealand.
Franzetti, S., Malavasi, S., and  Piccinin, C. (1994). sull’erosione alla base pile di ponte in acquechiare. Proc., XXIV Convegno di Idraulica e Costruzioni Idrauliche, vol. 2, T4 13-24 (in italian).
Grimaldi, C. (2005). "Non-conventional countermeasures against local scouring at bridge piers", PhD Thesis, University of Calabria, Cosenza, Italy.
Guo, J., Suaznabar, O., Shan, H., and Shen, J. (2012). "Pier scour in clear-water conditions with non-uniform bed materials" (No. FHWA-HRT-12-022).
Hannah, C.R. (1978). "Scour at pile groups". Report No. 78-3, M.S. Thesis, Canterbury University, Canterbury,  New Zealand.
Khaple, S. K., Hanmaiahgari, P. R., and Dey, S. (2014). "Studies on the effect of an upstream pier as a scour protection measure of a downstream bridge pier", Riverflow, Lausanne, Switzerland.
Khaple, S., Hanmaiahgari, P.R., Gaudio, R., and Dey, S. (2017). "Interference of an upstream pier on local scour at downstream piers". Acta Geophys. 65(1), pp. 29–46.
Lanca, R.,  Fael, C., Maia, R., Pego, J.P., and Cardoso, A.H. (2013). "Clear-Water Scour at Pile Groups". J. Hydraulic Eng. 139, pp.1089–1098.
Laursen, E.M. and Toch, A. (1956). "Scour Around Bridge Piers And Abutments". Bulletin No.4. Iowa Highways Research Board. Ames. IA.
Melville, B.W. and  Sutherland, A.J. (1988). "Design Method for Local Scour at Bridge Piers". J. Hydraulic Eng. 114(10), pp.1210–1226.
Melville, B.W. and Chiew, Y.M. (1999). "Time scale for local scour at bridge piers". J. Hydraulic Eng. 125(1), pp.59-65.
Sheppard, D.M. and Renna, R. (2005). "Bridge scour manual". Florida Department of Transportation, 605.
Sheppard, D. M. and Renna, R. (2010). "Florida Bridge Scour Manual". Florida Department of
Transportation, Tallahassee, FL.
Sheppard, D.M., Melville, B., and Demir, H. (2013). "Evaluation of Existing Equations for Local Scour at Bridge Piers". J. Hydraulic Eng. 140(1), pp.14–23.
Tafarojnoruz, A., Gaudio, R., and Calomino, F. (2012). "Evaluation of Flow-Altering Countermeasures against Bridge Pier Scour". J. Hydraulic Eng. 138(3), pp. 297–305.
Zhao, G. and Sheppard, D. M. (1999). "The effect of flow skew angle on sediment scour near pile groups". Stream Stability and Scour at Highway Bridges. Compilation of Conference Papers. ASCE. Reston. VA, 377–391.
  • Receive Date: 23 October 2018
  • Revise Date: 17 December 2018
  • Accept Date: 14 January 2019
  • First Publish Date: 21 March 2019